1、生成二维码的工具类
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import lombok.extern.slf4j.Slf4j;
import org.springframework.util.StringUtils;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;

@Slf4j
public class WxQrCode {

    //获取AccessToken路径
    private static final String AccessToken_URL
            = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=APPID&secret=APPSECRET";//小程序id
    //获取二维码路径
    private static final String WxCode_URL
            = "https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token=ACCESS_TOKEN";//小程序密钥
    /**
     * 用于获取access_token
     * @return  access_token
     * @throws Exception
     */
    public static String getAccessToken(String appid,String secret) throws Exception {
        String requestUrl = AccessToken_URL.replace("APPID",appid).replace("APPSECRET",secret);
        URL url = new URL(requestUrl);
        // 打开和URL之间的连接
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("POST");
        // 设置通用的请求属性
        connection.setRequestProperty("Content-Type", "application/json");
        connection.setRequestProperty("Connection", "Keep-Alive");
        connection.setUseCaches(false);
        connection.setDoOutput(true);
        connection.setDoInput(true);

        // 得到请求的输出流对象
        DataOutputStream out = new DataOutputStream(connection.getOutputStream());
        out.writeBytes("");
        out.flush();
        out.close();

        // 建立实际的连接
        connection.connect();
        // 定义 BufferedReader输入流来读取URL的响应
        BufferedReader in = null;
        if (requestUrl.contains("nlp"))
            in = new BufferedReader(new InputStreamReader(connection.getInputStream(), "GBK"));
        else
            in = new BufferedReader(new InputStreamReader(connection.getInputStream(), "UTF-8"));
        String result = "";
        String getLine;
        while ((getLine = in.readLine()) != null) {
            result += getLine;
        }
        in.close();
        JSONObject jsonObject = JSON.parseObject(result);
        String accesstoken=jsonObject.getString("access_token");
        return accesstoken;
    }


    /*
     * 获取 二维码图片
     *
     */
    public static InputStream getminiqrQr(String accessToken,String scene, String page) {
        InputStream is = null;
        try
        {
            String wxCodeURL = WxCode_URL.replace("ACCESS_TOKEN",accessToken);
            URL url = new URL(wxCodeURL);
            HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
            httpURLConnection.setRequestMethod("POST");// 提交模式
            // conn.setConnectTimeout(10000);//连接超时 单位毫秒
            // conn.setReadTimeout(2000);//读取超时 单位毫秒
            // 发送POST请求必须设置如下两行
            httpURLConnection.setDoOutput(true);
            httpURLConnection.setDoInput(true);
            // 获取URLConnection对象对应的输出流
            PrintWriter printWriter = new PrintWriter(httpURLConnection.getOutputStream());
            // 发送请求参数
            JSONObject paramJson = new JSONObject();
            if(!StringUtils.isEmpty(scene)){
                paramJson.put("scene", scene);
            }
            if(!StringUtils.isEmpty(page)) {
                paramJson.put("page", page);
            }
//            paramJson.put("page", "pages/index/index"); //小程序暂未发布我没有带page参数
            paramJson.put("width", 430);
            paramJson.put("is_hyaline", true);
            paramJson.put("auto_color", true);

            printWriter.write(paramJson.toString());
            // flush输出流的缓冲
            printWriter.flush();
            //开始获取数据
            is = httpURLConnection.getInputStream();
        }catch (Exception e){
            e.printStackTrace();
        }
        return is;
    }

    public static void main(String[] args) {
        String APIKEY = "wxbc6e00e3f4ba7128";
        String SECRETKEY = "4db0fdadb56a95fb6d29ba78b5d9dd21";
        String accessToken = null;
        try{
            accessToken = WxQrCode.getAccessToken(APIKEY,SECRETKEY);
            System.out.println("accessToken;"+accessToken);
            InputStream is = WxQrCode.getminiqrQr(accessToken,"1","pages/common/vip/vipJoin");

            String filepath = "C:\\Users\\10320\\Desktop\\c.jpg";
            FileOutputStream os = new FileOutputStream(filepath);

            byte[] bytes = new byte[1024];
            int length;
            while((length = is.read(bytes))>0){
                os.write(bytes,0,length);
            }
            os.close();
            is.close();
        }catch (Exception e){
            e.printStackTrace();
        }
    }

}